Device for accelerating the ignition of the propellant for a projectile



March 1, 1960 w. w. ATKINS ETAL 2,926,566 DEVICE FOR ACCELERAT G THE IGNITION OF THE OPELLANT A PROJECTILE iled No 1956 TOR5 INVEN R w. ATKINS W. BIXBY JR.

WALTE PAUL BY WW HIGH ENE sou ATTORNEY5 DEVICE FOR ACCELERATING THE IGNITION OF THE PROPELLANT FOR A PROJECTILE Walter W. Atkins, Alexandria, Va., and Paul W. Bixby,-

Jr., Riverdale, Md., assignors to the United States of America as represented by the Secretary of the Navy Application November 30, 1956, Serial No. 625,555 1 Claim. (Cl. 89f28) (Granted under Title 35, U.S. Code (1952),.sec. 266;) f,

The invention described herein maybe manufactured and used by or for the Government, of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a new device and method for accelerating the ignition of a solid, liquid or gaseous material and more particularly to accelerating the ignition of the propellant for a projectile without the use of a primer.

In firing projectiles, the propellants used aregenerally in the solid state and function by rapid transformation into gaseous products with the simultaneous evolution of heat, this change of state developing the necessary pressure to produce movement of the projectile. The necessary pressure is developed by the propellant converting into gas which builds up within the cartridge casing to force the projectile from the casing. The propellant is not easily ignited by direct ignition therefore, prior art devices use an easily ignited primer which burns rapidly building up sufficient heat and pressure to ignite the main propellant, The primer contains a small quantity of very sensitive igniting material which initiates burning of the propellant and it is extremely essential that a primer fire under certain conditionsso care must be exercised in the design of the components to insure proper functioning thereof. Cartridge primers are usually situated in or near the head of the casing and when the cartridge is fired the primer initiates an explosive train from the head toward the projectile. 'As the propellant burns, pressure builds up until the projectile is expended from the casing and then the propellant continues to burn until the projectile leaves the gun barrel. In these devices it is necessary that the primer operate satisfactorily in igniting the main propellant in order to obtain maximum results from the main propellant.

Since the propellant burns from the head longitudinally of the propellant toward the projectile, pressure builds up accordingly and is greatest at the headdue tothe pressure build-up during burning awaytrom the head. In order to provide constant pressure and burning over the full length of the propellant for more eflicient results, it is necessary for the propellant to burn radially from the center thereof along the whole length. Radial burning provides even, instant burning which produces greater efficiency, increased energy and increased velocity for the projectile.

It is an object of the present invention to provide a new device for igniting the propelling charge of a cartridge.

Another object is to provide a new and improved device for firing projectiles at increased velocities.

A further object is to provide radial burning along the entire length of a cylindrical propellant.

Still another object is to provide means for igniting the propelling charge of a cartridge without the use of a primer.

Yet another object is to provide a new device for ignition of a solid, liquid, or gaseous material.

The exact nature of this invention as well. as other objects and advantages thereof will be readily apparent 5 ing through the length of the propellant 16 and then is from consideration of the following detailed description relating to the annexed drawings in which:

Fig. 1 illustrates a cross sectional viewrofa preferred embodiment of a cartridge tion;

Figs. 2 and 3 illustrate modified forms of the cartridge of Fig. 1; and

'Fig. 4 is a sectional view of a cartridge and the electrical firing means.

gaseousmaterial applied to accelerate projectiles. The

device makes use of a standard metal casing modified to have an electrical contact insulatedfrom the headof .the casing and a low resistance ignition wire attachedthereto which passes centrally 'along the lengthof the propellent chamber and is grounded to the casing. The, wire produces an ignition channel throughout thelength; of the propellant such that .the surface area of combnstion will be constantly increasing perpendicular to the",

entire length of the channel. A source of high electrical energy is passed through the Wire which "instantaneous v ly explodes the wire causing a rapid, evenignition of? the propellant to expel the projectile. The arrangement of the exploding wire in the casing provides combustion of the propellant without the use of a primer, and pro-; vides greater efiiciency and increased energy of the pro," pellant as well as increased velocity for the projectiler f v Referring now to the drawings wherein like reference, characters represent like parts throughou t the cartridge, as illustrated in Fig. 1, comprises a standardcasing 10' of thedesired calibre such'as 60, 50, 30, etc. The primer pocket 11 of the head 12 has been modified to .provide space in which an insulator 13 such as Bakelite hasbeeni pressed. The insulator has a threaded hole'through the center thereof for receptionof a metallic screw 14 which secures one end of a low resistance electrical conductor 15, suchras a wire, to the head end.-.The wire extends centrallyalong the longitudinal axis of the cartridge .cas-

attached to the side of the casing near the mouth. The cartridge is shown with a cotton wad 17 between the propellant 16 and the projectile 18. g

FigsQZ and 3 are modifications of Fig. lwhich illustrates respectively a 'straightwire 22 which is .brought' out near the mouth of the casing and makes. contact to the casing as in Fig. 1. w

4 illustrates a cartridge positioned in firing posi- 7 tion in a gun chamber 23 and backed'by a specially designed breech 24 to prevent back'pressureleaks; Electrical contact for the wire in the cartridge is provided as used for radar transmitters, modulators or any elec-, trical device which will supply a large current through' the wire for a short interval. A preferred source will deliver a pulse'of energy at a potential of 50,000 volts.

Carttridges are easily made (see Fig. '1) by drilling a hole in the side thereof near the mouth end, leaving out the usual primer, then milling the head to provide space for the insulator insert -13. The insert is pressed into Patented Mar. 1, 1960 made according to the invenartridge positionedin a gun chamber and illustrates the relationship between the with. theprojectile .and a spiral wire which is attached the head and then a screw 14 having a hole centrally along the longitudinal axis thereof is screwed into the insulator. The ignition wire is bent to form a 90 angle near one end and then the ends are pressed respectively through the hole in the screw and the hole in the side of the casing. The wire is held in position along the longitudinal axis of the casing and soldered to the screw and the casing, then the excess wire iscut ofi and the ends are smoothed down to the respective surfaces. After the wire is secured in place, a fine grain propellant is poured into the casing which surrounds the wire, a cotton wad 17 is inserted into the casing to hold the propellant into place and then the projectile isinserted into the mouth behind the cotton Wad to complete a high velocity cartridge. Inthe embodiment of Fig. 2 it is not necessary to bore a hole in the casing andthe cotton wad will hold the wire centrally along the casing and in contact with the projectile.

In operation of the device, a loaded cartridge such as shown in Figs. 1, 2 or 3 ispositioned in the gun chamber with the wire through the carttridge making electrical contact with the lead-in wire 25, and the casing of the cartridge making electrical contact with the gun chamber. The high energy electrical source is made operative and switch 29 is closed to complete the circuit to the ignition wire. On completion of the circuit, the high electrical energy passes through the wire within the cartridge causing the wire to disintegrate or explode to provide an ignition channel in the form of a high energy heat throughout the length of the propellant such that the surface area of combustion will be constantly increasing. The high energy heat produces immediate burning of the propellant radially from the exploded wire which produces greater pressures, higher temperature and greater energy release per unit of time than that of cartridges fired by a primer. The device of this invention provides burning of the propellant radially through the longitudinal length thereof whereas the propellants of the primer fired devices burn from the primer end to the projectile end. The difference in burning of the propellant produces a sizeable diiference in the pressure and energy released by the propellant.

The electrical energy applied to the ignition wire must be of suflicient current to explode or instantly evaporate the wire to completion. This energy must be greater than that required to raise the wire to its melting point, this excess in current is known as the explosion factor (E) which must be to 10 times as great as the energy required to melt the wire. The energy depending on the type of ignition wire used.

The spiral wire type of ignitor shown in Fig. 3 provides more heating surface throughout the propellant thereby providing instantaneous burning to more surface area of the propellant. Such an arrangement also produces greater pressure, high temperatures, and greater energy release per unit time than the present known primer fired cartridges.

The modification of Fig. 2.45 electrically the same as that of Fig. 1 except the wire extends entirely through the propellant and contacts the projectile which provides a ground through the casihglitofthe gun chamber and simplifies loading the cartridge. The chemical reaction is substantially the same as for the cartridge'of' Fig. l.

Cartridges fired according to this invention provide increased projectile velocities up to. about 25% above that of projectiles fired according to. present dayprimer systems and with the same amount of propellant: The preferred ignition wire is of low resistance such as tincopper wire #20. magnesium or aluminum ribbon but it can be any appropriate electrical-conducting material and only requires sutficient high current to. instantly explode the wire.

The device is not limited to a solid propellant such as double base progressive burning; biit can be a gas such as helium and hydrogen-oxygen "mixture? It should be understood, smears that the'foregoing disclosure relates to only preferred embodiments of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and scope of the invention as 'set 'forth in the appended, claim.

What is claimed is: 1

A primerless electrically fired cartridge combination comprising a casing, said casing having a mouth and an inseparable head, a projectile adapted to. be frictional'ly. secured within said mouth, anelectrical contact'cen trally disposed in the head of said casing and electrically insulated therefrom, a propellant adapted to be placed within said casing betweenthehead end and said projectile, an axially disposed electrically explodable conductor connected at one one end; to saidelectrical contact and extending axially through said'propellant; another end of said electrically explodable conductor being secured to provide a ground connection with said casing, means for passing electrical energy. through the conduc tor at about 10 toabout 10 times the energy required to melt the conductor, said conductor on exploding providing ignition of said propellant and producing radial burning of said propellant simultaneously throughout the length of said conductor, saidignition of said'propellant providing propellant force within said casing for expending said projectile.

References Cited in the fileof this patent UNITED STATESBATENTS France Jan. 1 6 1952 

